1. Technical Field
The present invention relates to a touch panel input device and a processing execution method, which are intended to display operation keys on a touch panel screen and facilitate depression of a predetermined operation key to control execution of target processing.
2. Description of the Related Art
In known conventional touch panel input devices, when a user presses an operation key displayed on a touch panel screen, an operation signal corresponding to the pressed operation key is generated to control execution of processing in various electronic devices. Examples of such a touch panel input devices include a resistive touch display, an optical touch display, and a capacitive touch display.
Other devices have been proposed, where even if plurality of operation keys displayed on a touch panel screen in close proximity are touched and selected, an operation key designated by a user can be effectively selected from among the plurality of operation keys (see Japanese Unexamined Patent Application Publication No. 5-66885, for example). The touch panel input device disclosed in Japanese Unexamined Patent Application Publication No. 5-66885 prioritizes a plurality of candidate operation keys touched by the user to select one operation key designated by the user from among the candidate operation keys based on the priorities and an analysis of the touch input.
Touch panel input devices are installed in many vehicles, for example, in use with navigation systems or AV systems. However, such touch panel screens are relatively small and thus, the corresponding operation keys are also small. In addition, a plurality of operation keys are arranged in close proximity to each other on the touch panel screen rendering it difficult to accurately touch a target position with a finger due, especially when the vehicle is moving.
Therefore, the user might fail to press an intended operation key on the touch panel screen and may inadvertently depress multiple keys. In this case, processing corresponding to an unintended operation key might be executed.
As described above, if a vehicle equipped with a touch panel screen causes vibrations, a user may not be able to properly depress the key as intended. Therefore, even if analysis of the touch input is performed, as disclosed in Japanese Unexamined Patent Application Publication No. 5-66885, an intended operation key cannot be always specified.
If processing, which corresponds to an unintended operation key is executed, a user may be required to return to the previous operation screen and press the intended operation key again, which is a wasteful operation. In that regard, the processing executed in response to the erroneous user operation (multiple key press of plural operation keys) must be cancelled, and processing corresponding to an intended operation key is executed instead. This is inconvenient to the user.
Next, the above disadvantages of know devices is described with reference to the drawings. FIG. 13 shows an example of a touch panel screen displayed on a display panel. The touch panel screen (operation screen) 10 displays nine thumbnail images (operation keys), by which a user selects a chapter to execute video playback processing of the chapter. Each thumbnail image corresponds to the opening scene of each chapter.
For example, consider that a user tries to reproduce a chapter in a movie recorded on a DVD by pressing an intended operation key (for example, No. 3) on the operation screen 10. In this case, if the user presses multiple operation keys (Nos. 3 and 6) by mistake, a chapter corresponding to the unintended operation key (No. 6) would be reproduced. The user must then return to the previous operation screen 10 and represses the intended operation key (No. 3). This is very inconvenient to the user.
Further, if it is difficult to identify which thumbnail image corresponds to a target chapter by merely viewing thumbnail images, a user may need to guess which thumbnail image corresponds to the target chapter, and may try to press one of the operation keys (thumbnail image) and then check to determine if a reproduced chapter is the correct choice. If the reproduced chapter is not the intended chapter, the user must return to the previous operation screen 10 each time. Again, this if very inconvenient for the user.